User manual

Computer Gateway User Manual 4-55 5/96
4.7.2
4.7.2 Get Single Point Request (External Identifier)
This request from the host processor is used to fetch a single value (or an array of values)
for a point and parameter specified in the ACP's calling sequence, using the external
identifier.
Eight-Character Tagname Form
Header information: Word 1—Transaction Code = 28
Word 2—Number of Words = 16
Word 5—CG Identifier = 2
Message format: Words 1..4—ACIDP name or blank (8 ASCII characters)
Word 5—data access priority (integer) 1=control
2=noncontrol
Word 6—data type (integer) 1=real
2=integer
3=ASCII (24 character string)
4=enumeration/boolean
5=enumeration ordinal value
6=LCN external time (see 4.7.3)
7=real array
8=integer array
9=enumeration array
10=ordinal values array
13=internal entity id
14=internal entity id array
15=external entity id (ASCII name)
16=external entity id array
17=LCN internal time
18=LCN internal time array
19=ASCII (40 character string)
20=ASCII (40 char. string) array
Words 7..10—point name (8 ASCII characters)
Word 11—point name index (integer)
Words 12..15—parameter name (8 ASCII characters)
Word 16—parameter array pointer/size (integer)
Use information: Point name index must = 0
Content of the field "parameter array pointer/size" depends on
data-type specification. See paragraph 4.7.1 for an explanation of
this field's use with single parameters and with parameter arrays.